hbase-user mailing list archives

If there is no objection, I will create a JIRA to increase the maximum
number of column families described here:
http://hbase.apache.org/book.html#number.of.cfs
Cheers
On Mon, Apr 8, 2013 at 7:21 AM, Doug Meil <doug.meil@explorysmedical.com>wrote:
>
>
> For the record, the refGuide mentions potential issues of CF lumpiness
> that you mentioned:
>
> http://hbase.apache.org/book.html#number.of.cfs
>
>
> 6.2.1. Cardinality of ColumnFamilies
>
> Where multiple ColumnFamilies exist in a single table, be aware of the
> cardinality (i.e., number of rows).
> If ColumnFamilyA has 1 million rows and ColumnFamilyB has 1 billion
> rows, ColumnFamilyA's data will likely be spread
> across many, many regions (and RegionServers). This makes mass
> scans for ColumnFamilyA less efficient.
>
>
>
>
>
> Š. anything that needs to be updated/added for this?
>
>
>
>
>
> On 4/8/13 12:39 AM, "lars hofhansl" <larsh@apache.org> wrote:
>
> >I think the main problem is that all CFs have to be flushed if one gets
> >large enough to require a flush.
> >(Does anyone remember why exactly that is? And do we still need that now
> >that the memstoreTS is stored in the HFiles?)
> >
> >
> >So things are fine as long as all CFs have roughly the same size. But if
> >you have one that gets a lot of data and many others that are smaller,
> >we'd end up with a lot of unnecessary and small store files from the
> >smaller CFs.
> >
> >Anything else known that is bad about many column families?
> >
> >
> >-- Lars
> >
> >
> >
> >________________________________
> > From: Andrew Purtell <apurtell@apache.org>
> >To: "user@hbase.apache.org" <user@hbase.apache.org>
> >Sent: Sunday, April 7, 2013 3:52 PM
> >Subject: Re: schema design: rows vs wide columns
> >
> >Is there a pointer to evidence/experiment backed analysis of this
> >question?
> >I'm sure there is some basis for this text in the book but I recommend we
> >strike it. We could replace it with YCSB or LoadTestTool driven latency
> >graphs for different workloads maybe. Although that would also be a big
> >simplification of 'schema design' considerations, it would not be so
> >starkly lacking background.
> >
> >On Sunday, April 7, 2013, Ted Yu wrote:
> >
> >> From http://hbase.apache.org/book.html#number.of.cfs :
> >>
> >> HBase currently does not do well with anything above two or three column
> >> families so keep the number of column families in your schema low.
> >>
> >> Cheers
> >>
> >> On Sun, Apr 7, 2013 at 3:04 PM, Stack <stack@duboce.net <javascript:;>>
> >> wrote:
> >>
> >> > On Sun, Apr 7, 2013 at 11:58 AM, Ted <yuzhihong@gmail.com
> >><javascript:;>>
> >> wrote:
> >> >
> >> > > With regard to number of column families, 3 is the recommended
> >>maximum.
> >> > >
> >> >
> >> > How did you come up w/ the number '3'? Is it a 'hard' 3? Or does it
> >> > depend? If the latter, on what does it depend?
> >> > Thanks,
> >> > St.Ack
> >> >
> >>
> >
> >
> >--
> >Best regards,
> >
> > - Andy
> >
> >Problems worthy of attack prove their worth by hitting back. - Piet Hein
> >(via Tom White)
>
>
>
>